为什么在删除动态分配的内存后，编译器没有自动将NULL分配给指针变量? [英] Why compilers do not assign NULL to pointer variable automatically after deleting dynamic allocated memory?

问题描述

我有一小段代码:

#include <iostream>
using namespace std;

int main() 
{
    int *p = new int(10);

    if(p != NULL)
    {
        cout<<"Deleted dynamic allocated memory"<<endl;
        delete p;
    }

    if(p == NULL)
    {
        cout<<"NULL"<<endl;
    }
    else
    {
        cout<<"Not NULL"<<endl;
    }
    return 0;
}

使用delete运算符删除动态分配的内存后，为什么编译器没有自动将NULL分配给指针(如p = NULL)?

After deleting dynamic allocated memory using delete operator, Why compilers do not assigned NULL to pointer(like p = NULL) automatically?

推荐答案

1. 这通常是不必要的，尤其是在编写良好的代码中.

1. It would often be unnecessary, particularly in well-written code.

它可以隐藏错误.

delete p;修改其自变量，则在语法上是特质的.

delete p; would be syntactically idiosyncratic if it modified its argument.

在(1)中，std::unique_ptr尤其浪费.

On (1) it would be particularly wasteful with std::unique_ptr.

换句话说，在必要时让程序员负担这项工作是正确的事情.

In other words, burdening the programmer with this job if necessary is the right thing to do.

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